package Alog;

import java.util.Scanner;

/**
 * @author : niu niu
 * @version : 1.0.0
 * @date : 2022/10/18 19:26
 */
public class Test4 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double sum = 0;
        double factor = 1;
        for (int i = 1; i <= 30; i++) {
            factor*=i;
            sum+=factor;
        }
        System.out.printf("%.2e\n",sum);
    }

}
